Due to the trend of metallic design, mobile communication devices nowadays usually have a metal outer frame. In practice, the mobile communication devices further have a plastic frame body and a metal inner frame. To reduce the influence generated from the metal outer frame to the transmission quality of the mobile communication devices, the metal outer frame is usually connected to the metal inner frame, which is connected to the ground, via a conductive element. Furthermore, the connection impedance between the metal outer frame and the metal inner frame needs to be kept in a predetermined range to ensure that the influence generated from the metal outer frame on the mobile communication devices is reduced by the conductive element disposed.
For example, FIG. 1 is a structural schematic diagram of a plastic frame body of a conventional mobile communication device from the perspective that the display module of the mobile communication device faces the user. As shown in FIG. 1, an edge of a plastic frame body 110 has a plurality of apertures 121-124. When the conventional mobile devices are assembled, a metal outer frame (not shown) covers the plastic frame body 110 and is located at the left side of the apertures 121-124, and a metal inner frame (not shown) is mounted in the plastic frame body 110 and located at the right side of the apertures 121-124. Therefore, the plurality of apertures 121-124 are reserved in advance on the plastic frame body 110 in the conventional mobile communication device, such that conductive elements can be disposed in the apertures 121-124 (the conductive elements may not be disposed in all of the apertures), wherein the metal outer frame and the metal inner frame are electrically connected with each other via the conductive elements in the apertures 121-124.
However, in the configuration above, not only that a plurality of apertures have to be reserved on the plastic frame body 110 in advance, the conductive elements are embedded in the plastic frame body 110 and respectively covered by the metal outer frame and the metal inner frame. Namely, the plurality of apertures makes it more difficult to manufacture the plastic frame body 110. In addition, when the metal outer frame, the plastic frame body, and the metal inner frame are assembled, none of the conductive elements are exposed and all of the conductive elements are completely covered by the metal outer frame, the plastic frame body, and the metal inner frame. Moreover, during assembly, the conductive elements may be deformed or dislocated, rendering incomplete electrical connection that may not be told in the appearance after assembly.
Therefore, the testing personnel is not able to determine whether the electrical connection between the conductive elements and the metal inner/outer frames is complete, and fails to further detect the connection impedance between the metal inner frame and the metal outer frame. It should also be noted that since the mobile communication device usually has a plurality of conductive elements, when the connection impedance between the conductive elements and the metal inner/outer frames is abnormal, the testing personnel cannot determine which of the conductive elements induces the incomplete electrical connection. In other words, for the conventional mobile communication devices, the testing personnel cannot detect the connection impedance between the metal inner frame and the metal outer frame. Therefore, it cannot be determined whether the connection impedance between the metal inner frame and the metal outer frame is kept in a predetermined range.